A new class of twistor-like string models in four-dimensional space-time extended by the addition of six tensorial central charge (TCC) coordinates z mn is studied. The Hamiltonian of tensionless string in the extended space-time is derived and its symmetries are investigated. We establish that the string constraints reduce the number of independent TCC coordinates z mn to one real effective co...

Fermi coordinates (FC) are supposed to be the natural extension of Cartesian coordinates for an arbitrary moving observer in curved space-time. Since their construction cannot be done on the whole space and even not in the whole past of the observer we examine which construction principles are responsible for this effect and how they may be modified. One proposal for a modification is made and ...

The starting point of this work is the principle that all movement of particles and photons must follow geodesics of a 4-dimensional space where time intervals are always a measure on geodesic arc lengths, i.e. c(dt) = gαβdx dx , with c the speed of light in vacuum, t is time, gαβ is the metric tensor and x α represents any of 4 space coordinates. The last 3 coordinates (α = 1, 2, 3) are immedi...

The starting point of this work is the principle that all movement of particles and photons must follow geodesics of a 4-dimensional space where time intervals are always a measure of geodesic arc lengths, i.e. c(dt) = gαβdx dx , where c is the speed of light in vacuum, t is time, gαβ is the metric tensor and x α represents any of 4 space coordinates. The last 3 coordinates (α = 1, 2, 3) are im...

Abstract. The starting point of this work is the principle that all movement of particles and photons in the observable Universe must follow geodesics of a 4-dimensional space where time intervals are always a measure of geodesic arc lengths, i.e. c(dt) = gαβdx dx, with c is the speed of light in vacuum, t time, gαβ and the metric tensor; x α represents any of 4 space coordinates. The last 3 co...

The starting point of this work is the principle that all movement of particles and photons in the observable Universe must follow geodesics of a 4-dimensional space where time intervals are always a measure of geodesic arc lengths, i.e. c(dt) = gαβdx dx, with c is the speed of light in vacuum, t time, gαβ and the metric tensor; x α represents any of 4 space coordinates. The last 3 coordinates ...

In general, a physical system consists of a finite or infinite number of degrees of freedom which may or may not interact. The dynamics is prescribed by a set of evolution equations which follow from varying the action with respect to the different degrees of freedom. A symmetry then corresponds to a group of transformations on the space time coordinates and/or the degrees of freedom that leave...